nectocalyx

‖n.; pl. Nectocalyces [ NL., fr. Gr. nhkto`s swimming + &unr_; a calyx. ] (Zool.) (a) The swimming bell or umbrella of a jellyfish of medusa. (b) One of the zooids of certain Siphonophora, having somewhat the form, and the essential structure, of the bell of a jellyfish, and acting as a swimming organ. [ 1913 Webster ]